Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (02): 265-269.doi: 10.3866/PKU.WHXB20100206

• THERMODYNAMICS,THERMOCHEMISTRY AND SOLUTION CHEMISTRY • Previous Articles     Next Articles

Effects of Concentration and Freeze-Thaw Treatment on the Local Structure of Cu2+ in CuCl2 Aqueous Solutions

WANG Wen-Hua, ZHAO Lin, YAN Bo, TAN Xin, HE Bo, PAN Zhi-Yun   

  1. School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, P. R. China; National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, P. R. China
  • Received:2009-09-21 Revised:2009-11-09 Published:2010-01-26
  • Contact: ZHAO Lin E-mail:zhaolin@tju.edu.cn

Abstract:

The microscopic local environmental structure of Cu2+ ions in copper chloride solutions was investigated by X-ray absorption fine structure (EXAFS) spectroscopy. The effects of salt concentration and freeze-thaw (FT) treatment on the first coordination shell of Cu2+ were analyzed by examining the Cu K edge EXAFS spectra of CuCl2 aqueous solutions before and after FT treatment at various concentrations. The EXAFS results show that Cu2+ has 3.0-4.3 oxygen nearest neighbors with Cu—O bond length of 0.192 -0.198 nm in the first coordination shell. These structural properties can be ascribed to the Jahn-Teller effect. We found differences in the microscopic local structure of Cu2+ for various concentrations in CuCl2 aqueous solutions.With an increase in the salt concentration, the coordination number of Cu2+ decreases and the Cu—O bond length increases in the first coordination shell. The influence of FT treatment on the microscopic local environmental structure of Cu2+ was determined fromthe fitting results of the structural parameters. The coordination number of Cu2+ in its first coordination shell and the degree of thermal disorder increase when the FT treatment is operated in CuCl2 aqueous solutions.

Key words: EXAFS, CuCl2 aqueous solution, Structure of hydrated ion, Coordination number, Concentration, Freeze-thaw treatment

MSC2000: 

  • O645